For treatment of diseases associated with functional disturbances in the immune system, there are known methods operating by suppression of lymphocytes.
There is known a method for producing a therapeutic effect upon the organism, disclosed in PCT/GB88/00951, which comprises withdrawal of lymph from the thoracic duct of a patient, irradiating the lymph withdrawn by ultraviolet light, and returning the irradiated lymph to the lymphatic system of the patient.
When exposed to ultraviolet radiation, lymphocytes undergo direct degradation leading, in the final analysis, to their death. Considering the fact that most of the lymphocytes are pathologic cells, it is pathologic lymphocytes that are mainly destroyed. Thence the therapeutic effect.
However the lymphocytes so irradiated are not sufficiently immunogenic. That is to say, when these are introduced into the lymphatic system, the healthy immunocompetent cells of the lymphoid tissue are not capable of effecting a reaction when in contact with irradiated lymphocytes, such that would originate an immune response aimed at degradation or suppression of the functional and metabolic activities of such pathologic cells by the organism itself.
To achieve effective suppression of the pathologic lymphocytes by the organism itself, there is added to the biological fluid enriched with lymphocytes a photo-active chemical agent which has a specific affinity for the receptor sites in or on the constituents of said biological fluid, which is activated by ultraviolet radiation, and which is capable, when activated by said ultraviolet radiation, of forming photo-adducts with receptor sites of the constituents of said biological fluid, thereby assuring chemical linkage between said photo-active chemical agent and said receptor sites.
Added to the biological fluid enriched with lymphocytes, the photo-active chemical agent is adsorbed on the cell membranes, cell nucleus membranes, and cell and nucleus contents, as well as on the constituents of the intracellular fluid. Affected by ultraviolet radiation, the photo-active chemical agent passes into an active state and becomes highly reactive. In such a state, some photo-active chemical agents, e.g. of the furocoumarin class, form covalent linkages between the pyrimidines of the complementary DNA chains in a cell's nucleus, thereby preventing the possibility of divergence of DNA chains when the cell divided. In this manner, lymphocyte proliferation is prevented.
At the same time, affected by ultraviolet radiation, the photo-active chemical agent adsorbed at the receptor sites in or on the biological fluid constituents will either considerably intensify the photochemical reactions occurring under the effect of ultraviolet radiation (oxygen-dependent free radical reactions of cellular membrane lipids), which leads to changes in the receptor field of the membranes and their antigenic determinants, or increase the agent's specific effect level (when this agent is a carrier-photo-active group complex, and the carrier is a biologically active moiety having a specific suppressive effect upon immunocompetent cells, e.g. antibodies, cortisone, etc.). Thus, in said processes, the therapeutic effect is achieved by directly destroying or suppressing the functional and metabolic activities of the treated cells, which leads to a decrease in the cell concentration in the treated fluid, while, on the other hand, introduction into the organism of treated cells and fragments thereof with heavily changed antigenic structures (this being due to the formation-owing to the effect of ultraviolet irradiation-of photo-adducts comprising cellular components and photo-active chemical agent molecules) leads to the formation of an immune response by the organism, which is purposed to suppress the population of pathologic cells. Since the concentration of pathologic cells essentially exceeds that of healthy ones and also because it is in these that metabolic processes are most active, the photochemical effect is primarily upon pathologic cells, and it is these cells that are capable of causing-following the formation of covalent bonded stable photo-adducts and introduction of these into the organism-a systemic immune response aimed thereagainst.
U.S. Pat. No. 4,613,322 discloses a method for producing therapeutic effect upon the organism, comprising withdrawal of blood from a patient, centrifuging the blood drawn to separate red blood cells and most of the plasma, and obtaining a fraction, in which lymphocytes make the predominant cellular constituent. Said lymphocyte-rich fraction is then exposed to irradiation by ultraviolet light in the presence of a dissolved photo-active chemical agent which is introduced into the organism of the patient 2 hours before blood withdrawal. The blood fraction so irradiated is then returned to the blood supply system of the patient.
When said irradiated blood fraction is returned to the blood channel, the immunogenic photo-adducts formed by exposure to ultraviolet radiation with the participation of constituents of the treated fluid and molecules of the photo-active chemical agent and present in said blood fraction, are not in a position to interact with healthy intact lymphocytes circulating with the blood because, firstly, to provide for said therapeutic effect, the major part (up to 75%) of the immunocompetent cells (lymphocytes) available in the blood supply system of the patient must be exposed to radiation, and, secondly, the presence of other cellular elements in the blood, primarily erythrocytes, hinders direct contact between immunogenic photo-adducts and healthy cells. As regard the main immune response initiated by the emergence in the organism of changed antigenic structures as a result of photo adducts being introduced into the blood supply system, it is mainly localized within the spleen. But even the spleen receives but a limited portion of these immunogenic photo-adducts. This is due to the fact that a substantial part of these immunoreagents to be found in the blood gets attached to the surfaces of macrophages, and since the entire blood passes through the liver where a large number of macrophages is to be found, the major part of the immunogenic adducts introduced into the blood becomes concentrated in the liver, as well as in the kidneys and lungs, and only the remaining portion (up to 10% of the total quantity) falls to the share of the spleen.
This is what reduces the therapeutic effect provided by exposure to radiation.